The invention relates to a line standard conversion circuit for converting an interlaced television signal having a given number of lines per picture into a converted television signal having substantially double the number of lines per picture while maintaining the field frequency, the conversion circuit comprising a converter and an interpolator.
Philips Research Reports 29, 1974, pages 413-428 discloses a line standard conversion circuit of the above-mentioned type in which the converter converts the signal relating to the lines of a 313-line television picture into a signal relating to the lines of a 625-line television picture. Because the converter can supply information for only every alternate line of the 625-line picture, it is followed by an interpolator which, by means of one or more line stores, adds the missing lines in the 625-line picture and composes the signals of the lines of the 625-line picture from the signals of different lines of the 313-line picture.